In a Network Element (NE) with a large number of external Synchronous Optical Network (SONET) signal inputs there will be a large number of different overhead signals to be cross-connected, terminated and/or processed. Some of the types of overhead are naturally and easily taken care of, in that they are either carried with the transmission payload across an NE or they are terminated at an external interface. Such an external interface would be a unit of equipment having external inputs and outputs to the NE and having the ability to perform functions on these input/output signals prior to passing information elsewhere in the NE. Although these types are important, the classes of particular interest here are the remainder.